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LibJS/JIT: Use the x86_64 setcc instruction to remove a branch

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Bastiaan van der Plaat 2023-11-13 17:41:05 +01:00 • committed by Andreas Kling
parent 1d76738dde
commit d3b3e49e19
3 changed files with 17 additions and 16 deletions
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8
Userland/Libraries/LibJIT/X86_64/Assembler.h
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@ -569,6 +569,14 @@ struct X86_64Assembler {
jump_if(condition, label);
}
void set_if(Condition condition, Operand dst)
{
emit_rex_for_slash(dst, REX_W::No);
emit8(0x0f);
emit8(0x90 | to_underlying(condition));
emit_modrm_slash(0, dst);
}
void sign_extend_32_to_64_bits(Reg reg)
{
mov32(Operand::Register(reg), Operand::Register(reg), Extension::SignExtend);

24
Userland/Libraries/LibJS/JIT/Compiler.cpp
View file

@ -1098,27 +1098,19 @@ void Compiler::compile_mul(Bytecode::Op::Mul const& op)
Assembler::Label end {}; \
\
branch_if_both_int32(ARG1, ARG2, [&] { \
Assembler::Label true_case {}; \
\
m_assembler.sign_extend_32_to_64_bits(ARG1); \
m_assembler.sign_extend_32_to_64_bits(ARG2); \
\
m_assembler.jump_if( \
/* accumulator = SHIFTED_BOOLEAN_TAG | (arg1 condition arg2) */ \
m_assembler.mov( \
Assembler::Operand::Register(GPR0), \
Assembler::Operand::Imm(SHIFTED_BOOLEAN_TAG)); \
m_assembler.cmp( \
Assembler::Operand::Register(ARG1), \
Assembler::Operand::Register(ARG2)); \
m_assembler.set_if( \
Assembler::Condition::AssemblerCondition, \
Assembler::Operand::Register(ARG2), \
true_case); \
\
m_assembler.mov( \
Assembler::Operand::Register(GPR0), \
Assembler::Operand::Imm(Value(false).encoded())); \
store_accumulator(GPR0); \
m_assembler.jump(end); \
\
true_case.link(m_assembler); \
m_assembler.mov( \
Assembler::Operand::Register(GPR0), \
Assembler::Operand::Imm(Value(true).encoded())); \
Assembler::Operand::Register(GPR0)); /* sets only first byte */ \
store_accumulator(GPR0); \
\
m_assembler.jump(end); \

1
Userland/Libraries/LibJS/Runtime/Value.h
View file

@ -104,6 +104,7 @@ static_assert((EMPTY_TAG & IS_NULLISH_EXTRACT_PATTERN) != IS_NULLISH_PATTERN);
static constexpr u64 TAG_EXTRACTION = 0xFFFF000000000000;
static constexpr u64 TAG_SHIFT = 48;
static constexpr u64 SHIFTED_BOOLEAN_TAG = BOOLEAN_TAG << TAG_SHIFT;
static constexpr u64 SHIFTED_INT32_TAG = INT32_TAG << TAG_SHIFT;
static constexpr u64 SHIFTED_IS_CELL_PATTERN = IS_CELL_PATTERN << TAG_SHIFT;